There has been known a side curtain airbag that deploys an airbag body like a curtain between the side of the vehicle body and occupants and thereby widely protects the occupants when an impact is input at the time of a vehicle side collision, rollover, or the like.
The side curtain airbag is stored between a vehicle body pillar and a garnish (interior decoration member). Specifically, a garnish is attached to a vehicle body pillar so as to cover it, and an airbag body is stored in a folded state between the vehicle body pillar and the garnish. When an impact is input, high-pressure gas is ejected from an inflator, and thereby the airbag body is inflated. By this inflation pressure, the garnish can be moved while being pushed to open toward the interior of the vehicle. Thus, through a gap formed between the vehicle body pillar and the garnish, the airbag body is deployed in the interior of the vehicle, for example, so as to cover the entire surfaces of the side windows, like a curtain.
Examples of this type of side curtain airbag are shown in FIG. 12 and FIG. 13. The side curtain airbag 100 shown in FIG. 12 has an airbag body 110 that extends in the front-rear direction of a vehicle and covers front and rear side windows, and a plurality of fixation tabs 120 for attaching the airbag body 110 to the vehicle body.
The airbag body 110 is divided into a plurality of cells (air chambers) 101 that are inflated by high-pressure gas accumulated therein. The plurality of cells 101 are disposed substantially throughout the airbag body 110 in order to stably obtain the occupant protection performance. The upper periphery of the airbag body 110 has a shape corresponding to the shape of a vehicle opening 150 formed by the vehicle body pillars and the roof side rail. On the upper periphery of the airbag body 110 that follows the shape of the vehicle opening 150, the plurality of fixation tabs 120 are provided. The plurality of fixation tabs 120 are provided at positions corresponding to airbag fixation portions 151 disposed along the vehicle opening 150. For this reason, the frontmost fixation tab 120 (120A) is located below the other fixation tabs 120.
The side curtain airbag 200 shown in FIG. 13 is formed such that an airbag body 210 having a plurality of cells 201 extends linearly in the front-rear direction of the vehicle regardless of the shape of the vehicle opening 150. Thus, the frontmost fixation tab 220 (220A) is located at substantially the same level as the other fixation tabs 220.
The side curtain airbags 100 and 200 are both set by appropriately folding the airbag bodies 110 and 210 and then attaching the plurality of fixation tabs 120 and 220 to the airbag fixation portions 151.
In general, in the case where the airbag body deploys when an impact is input, the airbag body deploys while pushing the garnish to open toward the interior of the vehicle, through a gap formed between the vehicle body pillar and the garnish. Thus, after the deployment of the airbag body, the garnish is away from the vehicle body pillar, and there is a possibility that the impact absorbing performance of the garnish itself obtained by being close to the vehicle body pillar is not sufficiently obtained.
It is known to provide an urging device, such as a coil spring, that urges the garnish toward the vehicle body pillar to obtain the impact absorbing performance of the garnish itself even after the deployment of the airbag body (see Japanese Unexamined Patent Application Publication No. 2007-283825).
In the conventional side curtain airbag shown in FIG. 12, the outline of the airbag body 110 follows the shape of the vehicle opening 150, and the frontmost fixation tab 120 (120A) is located below the other fixation tabs 120. Thus, when folding the airbag body 110, the airbag body 110 needs to be folded carefully such that the frontmost fixation tab 120 (120A) is not in a roll. For example, it is necessary to fold the airbag body 110 from its lower end into concertinas, or to roll the airbag body 110 to the position of the frontmost fixation tab 120 (120A) and to then fold the rest into concertinas as shown in FIG. 14. Folding the airbag body 110 in such complex manners takes time.
In contrast, in the case of the side curtain airbag 200 shown in FIG. 13, the frontmost fixation tab 220 (220A) is located at the same level as the other fixation tabs 220, and thus the airbag body 210 can be rolled from its lower end as shown in FIG. 15. In this regard, this side curtain airbag 200 is favorable. However, since the frontmost fixation tab 220 (220A) is located at the same level as the other fixation tabs 220, a space H is prone to be left between the frontmost fixation tab 220 (220A) and the frontmost cell 201 (201A) as shown in FIG. 13. For this reason, when the airbag body 210 is deployed, the frontmost cell 201 (201A) is away from the airbag fixation portion 151 of the vehicle opening 150, and the frontmost cell 201 (201A) is unstable and prone to move.
When an impact is input, the occupant protection performance is obtained also by the impact absorption by the garnish in cooperation with the deployment of the airbag body. In the above-described conventional side curtain airbag described in Japanese Unexamined Patent Application Publication No. 2007-283825, the impact absorbing performance of the garnish itself is improved by providing an urging device such as a coil spring. However, in this case, while the vehicle is moving, the urging device vibrates owing to various causes (for example, attachment error or play), and there is a possibility that an abnormal noise may be generated by it. In addition, this is likely to increase the cost and weight.